Common on 993. Check whether there is corrosion to the inner pad facing where the pad is not 'biting' correctly due to 'pad lift' Does it happen heavy braking from a high speed?

Some say it's warped discs but I've never been convinced discs can actually 'warp' given the thickness _________________Me? The 13th Duke of Wybourne? Here? In a sixth form girl's dormitory? At three o'clock in the morning? With my reputation? What were they thinking of?

Les RichardsTrainee

Joined: 09 Apr 2009Posts: 83Location: Harlow, Essex.

Posted: Sun Nov 26, 2017 9:06 pm Post subject: Brake shudder.

I had this a while back and posted on here. Consensus was worn bushes on front suspension but the guy who does the servicing - and had previously changed disks, pads and fixed the lifting plates in the callipers - rechecked the bushes and said they were OK.

Ended up getting the disks skimmed by Marcus Bailey in Soham. They were great after.

That was in 2015 and now I have the same problem returned. Light shimmy at low braking speeds, severe at 60+. Went back to the service guy on Friday and he says it's probably warped disks again, ruling out lifting plates and calliper/pad problems.

Just to add to the mix my tyres (Pirelli PZero) are due for replacement due to age. I had a similar problem on an IB where the tyres gave a near-constant vibration but could not be balanced as they were too old! That nice Paul Stephens paid for a new set, but that's another story.

Thought I read somewhere recently that Pirellis are prone to this after a certain amount of time. Ideally I would like to try different wheels/tyres on the front to rule out any problem with mine although I will need to change them soon in any event.

What make/age of tyres are you running?_________________Les Richards

993
Polar Silver
5152 MU

wozyImola

Joined: 06 Feb 2013Posts: 804Location: Worcestershire

Posted: Sun Nov 26, 2017 9:18 pm Post subject:

It will NOT be warped disks. Modern ventilated disks do not warp. In fact traditional non vented disks did not warp unless possibly tracked and not allowed to cool correctly. Simples.

I'd be looking at brake pads ..... if a bit of pad material stuck to the disk after being parked then a quick 15 miles blast with a bit of hard braking should clear them. It will shake the wheel for a while but then should clear it self.

If that doesn't clear it, then unless the tires have gone out of true, I'd be looking at a bust wheel bearing._________________Porsche Cars of Great Britain launched the 993 in the UK in early December 1993 registering 12 x UK cars on the 6th & 7th of that month; mine is one of them.

Ive had this on and off for a while. Slight steering wheel shimmy at 60mph without brakes applied and quite a nasty wobble/vibration when breaking from higher speeds. I jacked the front up to spin the wheels are there was a slight grab when rotating slowly. On closer inspection, there was a mark on the disc where the pads sat when the car is in storage. I had the discs skimmed and all was well. Now its back again. A friend of mine had similar. He gave it full ABS activating braking force from 100mph and it cured it. Mines back under a sheet now, but I'll be trying the same in Spring._________________Porsche 993 C2S
Ford Focus RS Mk1

Les RichardsTrainee

Joined: 09 Apr 2009Posts: 83Location: Harlow, Essex.

Posted: Sun Nov 26, 2017 10:35 pm Post subject: Brake shudder

Regular hard use of the brakes is recommended by the chap who services my car._________________Les Richards

993
Polar Silver
5152 MU

stevewakSpa-Francorchamps

Joined: 08 Jun 2013Posts: 343Location: UK

Posted: Mon Nov 27, 2017 9:50 am Post subject: Re: Brake shudder

Les Richards wrote:

Regular hard use of the brakes is recommended by the chap who services my car.

I'd go with Zingari here, pad lift or pad pick up. Had lift on the 944 fronts and the previous owner had them ground on the edges (bodge). Jackal's site has a good write up. Easy to spot as the pads will wear to a taper vertically. Pickup will clear with several hard applications. Also worth checking the wishbone bushes._________________Porsche 944 S2 Coupe Guards Red
Porsche 993 Coupe 9m RS Replica

Mike-MSpa-Francorchamps

Joined: 28 Jan 2010Posts: 254

Posted: Thu Dec 07, 2017 6:12 pm Post subject:

Had the same issue on and off for years change of disks and pads cured it. I think it may of reoccured as I may not of been running them in correctly. Last time I received better advice from a new mechanic and hey presto no issues._________________1994 Aventura 993 C2 manual

pierrebearNewbie

Joined: 27 Sep 2017Posts: 45Location: Jersey

Posted: Mon Dec 11, 2017 2:07 pm Post subject:

I'll be the first to admit that I am not very technical. Am sending the car to the local indy later this week so will let you know what he says (he does really know his stuff though as everyone in the area recommends him).

In the meantime, I had a chat with the selling garage who were *incredibly* kind and have said it is probably the discs...now have a new set of front discs sitting on my table too just in case it is a build up of residue etc.

Also check the track-rod ends, or as the americans call them tie-rods, as there is a rubber section that fails over time that displays the symptoms you describe through the steering.

pierrebearNewbie

Joined: 27 Sep 2017Posts: 45Location: Jersey

Posted: Tue Dec 12, 2017 1:46 pm Post subject:

Thanks lemoncurry - just as an FYI, I tried a little "Italian tune up" yesterday evening on my way home which has lessened the vibrations somewhat. I am confident it is going to be build up of pad material on the discs - will get the mechanic to give the system a once over and swap out the discs for the new ones I have bought. Hopefully all will be sorted completely very soon as obviously you want to have full confidence in the car's brakes...particularly given the weather that we are all having at the moment!_________________1995 Carrera 2 coupe manual, midnight blue
EX 2006 Carrera 4S coupe manual, basalt black
EX 2003 Mercedes SL500, green black (dark blue!)

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